Various types of medical devices, including needles, access cannulas and similar tools are percutaneously inserted into the body, for a number of therapeutic, diagnostic or other purposes. In many cases, insertion of such devices are performed with the aid of imaging technology, such as x-ray fluoroscopy, magnetic resonance imaging, CT scanning, and the like. These technologies are employed in order to monitor passage of the device through the skin and/or other tissues to ensure the device passes along a desired path or is finally located properly after the process of insertion. For instance, a physician, technician or other professional can monitor fluoroscopic images at least periodically as the device is inserted or placed to compare the position(s) of the device to body tissues visible under the particular imaging technology. If the professional notes that the device is not at or moving toward a desired location, the professional can reorient the device or extract it and re-perform the insertion.
Using vertebroplasty procedures as a particular example, a clinician inserts a needle percutaneously to vertebra(e) to be treated. When the needle is determined to be in the proper place relative to a vertebra, e.g. by imaging technology such as those noted above, the needle is inserted into the vertebra and a support material (e.g. bone cement) is injected into the vertebra. The clinician is faced with several challenges in inserting and positioning the needle for proper access to the body of a vertebra. The generally preferred access is through either pedicle of the vertebra to be treated. One common access technique begins with the obtaining of an oblique fluoroscopic view of the patient that is perpendicular to the pedicles of the vertebra of interest. The clinician then aligns the longitudinal axis of the needle with that oblique view, and inserts the needle though the skin and soft tissues of the patient until the needle tip contacts the pedicle.
If the insertion is performed without further imaging, there is naturally a risk of misplacement of the needle, with the necessity of moving the needle or perhaps extracting it and placing it all over again. Under fluoroscopy, if the clinician manipulates the needle directly, his or her hands can be exposed to radiation at least to the extent that the needle's handle is in the beam of the imaging equipment. Further, in using imaging equipment, parts of the equipment (such as the C-arm of an x-ray machine) can be in the way of the clinician as he or she places the needle. To avoid exposure of the clinician's hands to radiation, it is known to position and align the vertebroplasty needle under imaging radiation using a remote handle or hemostats that grip the needle. The beam is then turned off and the clinician directs the needle based on the noted access point and alignment angle. However, the clinician's understanding or memory of the access point and alignment angle may not be as precise as is necessary, or may be altered as insertion begins or continues. Where a vertebroplasty needle is not correctly placed, generally it must be removed and placed again, using some or all of the noted steps. As such needles are generally large (e.g. 10 to 15 gauge) multiple attempts to place the needle on or adjacent a pedicle with the proper angle for entry of the needle into the pedicle can cause substantial extra trauma to the soft tissues of the back.
Consequently, accurate placement of a percutaneously-placed needle or other treatment device or implement can carry significant risk of radiation exposure for the clinician, while reducing that risk can raise the chance of an improper placement of the implement. There remains a need for devices and methods for use with percutaneously-placed implements to improve the accuracy of placement of the implement while minimizing patient discomfort and exposure of the medical professional to radiation.